Next time it floods, we'll be ready

editor
•
Oct 29, 2015 at 12:53 PM

When Norwalk Creek flooded last summer, it did exactly what it was supposed to.

In 1978, the Federal Emergency Management Agency (FEMA) did a Flood Insurance Study and recognized the area around Norwalk Creek as a flood plain. It predicted what would happen when a "hundred-year storm" hit Norwalk. That's exactly what happened June 21 and 22 2006. It's also what happened almost 40 years earlier in the last "hundred-year storm."

Jim Bowling, project manager for Arcadis, studied Norwalk's flood last year and presented these and other findings at Tuesday night's council meeting.

Of course, the area around Norwalk Creek has always been a flood plain.

Over the course of time (in the geological sense), Bowling explained, the creek, which moves about twice as fast as the average creek, has meandered over the area and hollowed out the valley around it.

Since 1978, almost all the bridges and culverts in the flood plain have been replaced and some fill has been added, but all that did was lower the water level, at best, by a few inches or even a foot. The same buildings would have flooded with or without the changes.

Norwalk Mayor Sue Lesch said the culvert under Benedict Avenue was being replaced just as she entered office in 2004. ODOT built the new one to almost the same specifications as the preceding one ODOT's only requirement at the time being that it do no harm. People were concerned at the time that it would cause a similar back up.

There was more than a four-foot difference in the water level from one side of Benedict Avenue to the other.

Lesch admitted she could have pushed harder to build the bridge with a larger opening. But she isn't sure it would have made any difference.

All in all, as a result of the flooding, four roads were covered in water and 31 buildings were flooded flooded, according to FEMA means flooded into the first floor; it does not include flooding in the basement.

Twenty-five of those buildings are in the Water Street/Benedict Avenue area.

If the city built another culvert beneath Benedict Avenue, Bowling said, the 25 buildings that flooded in that area last June would be reduced to 13. It's one of the best results he's ever seen from a proposed plan, Bowling said.

A wall, no more than three feet high, alongside the railroad tracks next to Water Street, would reduce the buildings remaining in the flood plain to just 4.

The four buildings that would remain are Pizza Cravin', the street department, and two storage buildings.

The plan would cost the city $3.5 million, not including land acquisition for the wall. Bowling indicated that they planned to have those businesses that benefit donate the land.

The plan does include improvements to the storm sewers around Water Street to keep the wall from trapping water on its other side. Also, Bowling said, the city would need to commit to a certain amount of maintenace of the second culvert under Benedict to keep it from silting up.

Mayor Lesch said that it was her desire to seek FEMA funding for the plan, if council is willing. She said part of the value of the $50,000 study was that the FEMA grant proposal is already half-written.

The improvements proposed at Benedict Avenue and Water Street would do little or nothing to improve the situation at either Elm Street or South West Street.

Five homes flooded on both Elm Street and South West Street, according to the official report. Lucy Hokes, an Elm Street resident whose home flooded, said that eight or nine homes were in fact flooded on Elm.

The city has filed for grants on behalf of three of those homeowners to enable the city to buy their property and turn it into a park. Whether additional houses would be eligible for such grants is somewhat unclear.

FEMA, which issues the grants, looks for a long history of flooding, the mayor said.

Further, it was her impression, she said, that FEMA wanted to work its way up from the creek and would not accept unadjacent properties. After that was disputed, however, the mayor promised to look into it.

The only solution for the remaining homes is to flood-proof them. There is no grant available from FEMA to help pay for that, however, and it would be the responsibility of the individual home-owners to implement.

Bowling said they did investigate improving the Norwalk reservoir to prevent flooding throughout the area.

The reservoir is only built to provide drinking water, and its presence currently has essentially no effect, positive or negative, on the flooding of the creek.

The reservoir holds about 7 percent of the volume of water that was pushed through Norwalk Creek in June of last year. The additional water flows over it like it isn't there at all. It is after all, just a mid-point in the creek, council member Skip Wilde pointed out it is not the source of the creek. Its presence does not dump additional water into the creek in such a storm.

To make the reservoir into a flood protection device, Bowling said, would be "an order of magnitude" more expensive than the proposed solution.

Still, several Elm Street residents told council they were having continuing flooding problems. They asked if the creek needs to be cleaned out. Bowling said cleaning out the creek would have no effect on such a large storm, which is what he was hired to address. He also said that he did not study the individual homes that people were concerned about, or the subsequent storms, so he could not say why they were still having flooding problems.